Selective recurrent laryngeal nerve stimulation using a penetrating electrode array in the feline model

Abstract

Objectives/Hypothesis: Laryngeal muscles (LMs) are controlled by the recurrent laryngeal nerve (RLN), injury of which can result in vocal fold (VF) paralysis (VFP). We aimed to introduce a bioelectric approach to selective stimulation of LMs and graded muscle contraction responses.Study Design: Acute experiments in cats. Methods: The study included six anesthetized cats. In four cats, a multichannel penetrating microelectrode array (MEA) was placed into an uninjured RLN. For RLN injury experiments, one cat received a standardized hemostat-crush injury, and one cat received a transection-reapproximation injury 4 months prior to testing. In each experiment, three LMs (thyroarytenoid, posterior cricoarytenoid, and cricothyroid muscles) were monitored with an electromyographic (EMG) nerve integrity monitoring system. Electrical current pulses were delivered to each stimulating channel individually. Elicited EMG voltage outputs were recorded for each muscle. Direct videolaryngoscopy was performed for visualization of VF movement.Results: Stimulation through individual channels led to selective activation of restricted nerve populations, resulting in selective contraction of individual LMs. Increasing current levels resulted in rising EMG voltage responses. Typically, activation of individual muscles was successfully achieved via single placement of the MEA by selection of appropriate stimulation channels. VF abduction was predominantly observed on videolaryngoscopy. Nerve histology confirmed injury in cases of RLN crush and transection experiments.Conclusions: We demonstrated the ability of a penetrating MEA to selectively stimulate restricted fiber populations within the feline RLN and selectively elicit contractions of discrete LMs in both acute and injury-model experiments, suggesting a potential role for intraneural MEA implantation in VFP management.

Recurrent laryngeal motor nerve conduction studies in a rat model: Establishing an objective measure for investigating laryngeal innervation

“…Bhatt et al utilized cadaveric dissection, CT imaging, and ultrasound guidance to delineate the key landmarks and parameters that can be used to guide consistent transcutaneous stimulation of the RLN 21 . Others have attempted use of multielectrode array stimulation and transcranial magnetic stimulation to produce more consistent stimulation 19,20 . Perhaps by combining key anatomical landmarks, image guidance, and multiple stimulation paradigms and locations, consistent and clinically valuable data, including comparable measures of nerve conduction velocity, may be obtained.…”

“…21 Others have attempted use of multielectrode array stimulation and transcranial magnetic stimulation to produce more consistent stimulation. 19,20 Perhaps by combining key anatomical landmarks, image guidance, and multiple stimulation paradigms and locations, consistent and clinically valuable data, including comparable measures of nerve conduction velocity, may be obtained. Toward this end, our lab has begun performing open rlMNCS in anesthetized humans undergoing total laryngectomy.…”

“…Neuromuscular disease and aging have been shown to negatively affect the CMAP in the arm, 13 hand, 14 and leg muscles, 15 and are associated with poorer muscle function 16–18 . Prior studies have attempted to perform MNCS in the larynx but have had limited clinical or experimental utility 19–21 …”

“…[16][17][18] Prior studies have attempted to perform MNCS in the larynx but have had limited clinical or experimental utility. [19][20][21] The goal of this study was to explore the feasibility of performing recurrent laryngeal motor nerve conduction studies (rlMNCS) in the rat larynx. We hypothesize that application of rlMNCS in an in-vivo model may be useful for study of the neuromuscular changes that occur in the diseased or aging larynx and will provide a basis for prevention and treatment of diseases affecting laryngeal neurophysiology.…”

An Implantable System For Chronic In Vivo Electromyography

“…However, multiple EMG recordings over the entire period of reinnervation cannot be achieved by an invasive approach. Therefore, implantable devices have been designed and developed for repeated, chronic stimulation and recording in neuromuscular systems 6,7,8,9,10,11,12,13 . The aim of this paper is to describe a protocol for the manufacturing and implantation of a stable system for obtaining reliable chronological EMG data from the larynx.…”